Two-time Wimbledon champion Rafael Nadal of Spain became the victim of the first major upset of this year’s tournament, losing on Monday, 7-6 (4), 7-6 (10-8), 6-4 to unseeded Steve Darcis of Belgium on Court No. 1.

Nadal, seeded fifth, took a seven-month break because of a knee injury after he lost in the second round at Wimbledon last year but came back strong to assemble a 22-match winning streak that included a win at the French Open a few weeks ago. That streak was ended Monday by Darcis, who is ranked 135th in the world.

Nadal had never been eliminated in the first round of a major tournament.

Federer won, 6-3, 6-2, 6-0, taking only 18 minutes in the third set to launch his pursuit of a record eighth title.

No. 6 Jo-Wilfried Tsonga of France also advanced, with a 7-6 (4), 6-4, 6-3 victory over David Goffin of Belgium. John Isner of the U.S., seeded 18th, twice went to tiebreakers in defeating Evgeny Donskoy of Russia, 6-1, 7-6 (5), 7-6 (3).

Russia’s Maria Sharapova, the No. 3-seeded woman, had to work a bit harder in her opening match but defeated Kristin Mladenovic of France, 7-6 (5), 6-3. No. 2 Victoria Azarenka of Belarus also advanced, with a 6-1, 6-2 victory over Maria Joao Koehler of Portugal.

There was one notable early upset on the women’s side: No. 5 Sara Errani of Italy lost to unseeded Monica Puig of Puerto Rico, who took a 6-3, 6-2 decision.